We propose a new mechanism to preserve privacy while leveraging user profiles in distributed recommender systems. Our mechanism relies on two contributions: (i) an original obfuscation scheme, and ...(ii) a randomized dissemination protocol. We show that our obfuscation scheme hides the exact profiles of users without significantly decreasing their utility for recommendation. In addition, we precisely characterize the conditions that make our randomized dissemination protocol differentially private. We compare our mechanism with a non-private as well as with a fully private alternative. We consider a real dataset from a user survey and report on simulations as well as planetlab experiments. We dissect our results in terms of accuracy and privacy trade-offs, bandwidth consumption, as well as resilience to a censorship attack. In short, our extensive evaluation shows that our twofold mechanism provides a good trade-off between privacy and accuracy, with little overhead and high resilience.
To assess the safety and efficacy of a new simplified procedure for transfemoral (TF) transcatheter aortic valve replacement (TAVR): the FAST protocol.
A minimalist approach for TF-TAVR has been ...reported. The goal of this simplified strategy is to reduce the rate of specific complications associated with general anesthesia, second vascular access, and use of temporary pacemaker, and to reduce the length of stay.
We retrospectively reviewed all TF-TAVR cases performed at our center between January 2015 and December 2017. The FAST strategy consisted of local anesthesia with conscious sedation, echocardiographically guided TF puncture for main vascular access, radial approach for secondary arterial access, and left ventricular guidewire rapid pacing. Patients were sorted according to the initial strategy (FAST vs standard). The primary outcome was an early safety composite outcome including all-cause mortality, all stroke, life-threatening bleeding, acute kidney injury, coronary artery obstruction, major vascular complication, and valve-related dysfunction.
A total of 285 consecutive patients were included in the present analysis (76 FAST patients and 209 standard patients). There were no baseline differences between groups. Complete FAST procedure was feasible in 83.0% of cases and all FAST procedures were successful. The primary outcome was significantly lower in the FAST group (1.3% vs 14.3%; P<.001). The use of FAST protocol resulted in a reduction of major bleeding (1.3% vs 10.1%; P=.01), blood transfusion (2.6% vs 14.3%; P<.01), and vascular complications related to the secondary access (0.0% vs 5.3%; P=.04). The length of stay was also significantly lower in the FAST group (4.9 days vs 6.4 days; P<.01).
FAST can be safely performed and is associated with lower rates of iatrogenic complications and a shorter length of stay.
The ability to identify people that share one’s own interests is one of the most interesting promises of the Web 2.0 driving user-centric applications such as recommendation systems or collaborative ...marketplaces. To be truly useful, however, information about other users also needs to be associated with some notion of trust. Consider a user wishing to sell a concert ticket. Not only must she find someone who is interested in the concert, but she must also make sure she can trust this person to pay for it.
This paper addresses the need for trust in user-centric applications by proposing two novel distributed protocols that combine interest-based connections between users with explicit links obtained from social networks à-la Facebook. Both protocols build trusted multi-hop paths between users in an explicit social network supporting the creation of semantic overlays backed up by social trust. The first protocol, TAPS2, extends our previous work on TAPS (Trust-Aware Peer Sampling), by improving the ability to locate trusted nodes. Yet, it remains vulnerable to attackers wishing to learn about trust values between arbitrary pairs of users. The second protocol, PTAPS (Private TAPS), improves TAPS2 with provable privacy guarantees by preventing users from revealing their friendship links to users that are more than two hops away in the social network. In addition to proving this privacy property, we evaluate the performance of our protocols through event-based simulations, showing significant improvements over the state of the art.
We present and evaluate
FreeRec
, an anonymous decentralized peer-to-peer architecture, designed to bring personalization while protecting the privacy of its users.
FreeRec
’s decentralized approach ...makes it independent of any entity wishing to collect personal data about users. At the same time, its onion-routing-like gossip-based overlay protocols effectively hide the association between users and their interest profiles without affecting the quality of personalization. The core of
FreeRec
consists of three layers of overlay protocols: the bottom layer,
rps
, consists of a standard random peer sampling protocol ensuring connectivity; the middle layer, PRPS, introduces anonymity by hiding users behind anonymous proxy chains, providing mutual anonymity; finally, the top clustering layer identifies for each anonymous user, a set of anonymous nearest neighbors. We demonstrate the effectiveness of
FreeRec
by building a decentralized and anonymous content dissemination system. Our evaluation by simulation, our PlanetLab experiments, and our probabilistic analysis show that
FreeRec
effectively decouples users from their profiles without hampering the quality of personalized content delivery.
Summary Background Operator radiation exposure is high during coronary procedures. The radial access decreases the rate of local vascular complications but increases operator radiation exposure. As ...the X-ray exposure is related to the distance between the operator and the radiation source, the use of an extension tube between the proximal part of the coronary catheter and the ‘injection device’ might decrease operator radiation exposure. Aims To demonstrate that the use of an extension tube during coronary procedures performed through the radial approach decreases operator radiation. Methods Overall, 230 patients were included consecutively and randomized to procedures performed with or without an extension tube. Radiation exposure measures were obtained using two electronic dosimeters, one under the lead apron and the other exposed on the physician's left arm. Results A non-significant trend towards lower left-arm operator exposure was noted in the extension tube group (28.7 ± 31.0 μSv vs 38.4 ± 44.2 μSv, p = 0.0739). No significant difference was noted according to the type of procedure. Radiation levels were low compared with the series published previously and decreased for each operator during the study. Conclusion The use of an extension tube did not reduce operator radiation exposure during procedures performed through the radial approach. However, physician awareness was increased during the study due to the use of an exposed electronic dosimeter. The use of exposed electronic dosimeters could therefore be recommended to allow operators to improve their protection techniques.
PDF
